The oxidation of the title phosphines was examined by cyclic voltammetry and Fourier-transformed ac voltammetry in dichloromethane/TBAH. The chemical reversibility of the oxidations increases dramatically with greater steric congestion afforded by the dipp ligands. Rate constants for the attack by adventitious water on the one-electron oxidation products of the less congested members of the series undergo were measured; P(dipp)3+ is unreactive on the CV timescale . A pronounced inductive effect is also observed with the alkyl substituted compounds. Detailed studies of the heterogenous kinetics of the electron transfer were also performed. Activation energies of 18, 24, and 25 kJ mol-1 were found for oxidation of the compounds for which n = 1, 2, and 3, respectively. These values are all significantly greater than those calculated using the Born equation for outer sphere activation barriers; the relationship between steric congestion and the activation energy of electrooxidation is discussed.

Electro-oxidation of P(Ph)<sub>3-n</sub> (dipp)<sub>n</sub> (dipp = 2,6-diisopropylphenyl; n = 0, 1, 2, 3) in non-aqueous media: An investigation into the role of sterics on electrochemical behavior and activation parameters across a homologous series of phosphines

244th National Meeting (2012)

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Electro-oxidation of P(Ph)3-n (dipp)n (dipp = 2,6-diisopropylphenyl; n = 0, 1, 2, 3) in non-aqueous media: An investigation into the role of sterics on electrochemical behavior and activation parameters across a homologous series of phosphines

Electro-oxidation of P(Ph)_3-n (dipp)_n (dipp = 2,6-diisopropylphenyl; n = 0, 1, 2, 3) in non-aqueous media: An investigation into the role of sterics on electrochemical behavior and activation parameters across a homologous series of phosphines